The present application is based on Japanese Patent Application No. 2001-178217, which is incorporated herein by reference.
This invention relates to a terminal crimping die system for crimping and connecting a terminal to an electric wire.
A terminal crimping machine is operative to crimp a terminal to an end part of an electric wire. There has been provided a conventional terminal crimping machine that uses a crimping die system consisting of a crimper (or upper die) 10 and an anvil (or lower die) 11, as shown in FIG. 4.
The crimper 10 has a recess 13 opened toward the anvil 11, and is provided in such a way as to be able to move along the direction of gravity.
The anvil 11 is disposed under the crimper 10, and formed in such a way as to have a section shaped so that the anvil 11 can be fitted into the recess 13 of the crimper 10. The top surface of the anvil 11 is formed as a crimping face 14. A curved terminal receiving groove 14a, on which a terminal 15 is put, is provided in this crimping face part 14. The terminal 15 having a U-shaped section, in which a conductor is accommodated, is placed on the terminal receiving groove 14a. When the crimper 10 is lowered and both the anvil 11 and the crimper 10 vertically press the terminal 15, respectively, both the end parts of the terminal 15 each having a top part, which comes into contact with a wall of the recess, gradually and upwardly go along the walls, so that the end parts are inwardly pushed and then bent. Thus, as shown in FIG. 6, the terminal 15 encloses the conductor and is crimped and caulked onto the conductor in such a way as to dig thereinto.
Meanwhile, as shown in FIGS. 4 and 5, the anvil 11 is provided with the terminal receiving groove 14a so that each of both end parts of the groove 14a is spaced from a corresponding one of both the end parts of the crimping face 14 toward the center thereof. That is, each of receiving surfaces 14b each extending along a direction nearly perpendicular to a direction, in which the anvil 11 is fitted, is provided between a corresponding one of both end parts of the terminal receiving groove 14a and that of both end parts of the crimping face 14. This is configured by taking the durability of the anvil 11 into consideration. However, when the terminal 15 to be crimped is small, the (plate) thickness thereof is small and sometimes almost similar to the width b of each of the receiving surfaces 14b. 
When the plate thickness of the terminal 15 is comparable to the width b of each of the receiving surfaces 14b, and the terminal 15 is crimped onto the wire in this way, stress is concentrated on a part of the crimped terminal 15 (that is, a part B shown in FIG. 6). That is, when the terminal is crimped, a caulking force f is generated in each crimped part, the receiving surface 14b bears the caulking force f generated in the vicinity thereof, so that the stress is concentrated on a part of the crimped terminal 15 (that is, the part B shown in FIG. 6). Practically, for example, when a terminal having a terminal plate thickness of 0.25 mm is crimped by using 0.22-mm-wide receiving surfaces, stress is concentrated on a part of the crimped terminal 15 (that is, the part B shown in FIG. 6). When stress is concentrated on a part of the terminal 15, the durability of the terminal 15 may be degraded. Moreover, the electrical connecting performance thereof may be deteriorated. Furthermore, sometimes, the terminal 15 is not favorably connected to the wire.
Accordingly, the invention is accomplished in view of such circumstances. An object of the invention is to provide a terminal crimping die system enabled to favorably crimp a terminal to an electric wire without concentrating stress on a part of the terminal.
To achieve the foregoing object, according to the invention, there is provided a terminal crimping die system comprising: a crimper including a recess; an anvil provided with a crimping face including a terminal receiving groove and a pair of receiving surfaces, each of which is formed between an end part of the terminal receiving groove and an end part of the crimping face, the anvil being configured to be inserted into the recess of the crimper to thereby crimp and connect a terminal to an electric wire; wherein a width of the receiving surface is not more than xc2xd of a thickness of the terminal.
Preferably, the width of each of the receiving surfaces ranges from ⅕ to ⅖ of the thickness of the terminal.
With such a configuration, when the terminal is crimped, a caulking force is generated in each crimping part, the caulking force generated in the vicinity thereof partly acts in a direction toward the inside of the terminal receiving groove and is deconcentrated. This prevents the stress from being concentrated on a part of the terminal (that is, a part A shown in FIG. 3), and enables the favorable crimp-connection of the terminal to an electric wire.
Further, in the present invention, a terminal crimping method comprising the steps of:
providing a crimper including a recess and an anvil provided with a crimping face including a terminal receiving groove and a pair of receiving surfaces, each of which is formed between an end part of the terminal receiving groove and an end part of the crimping face;
putting a terminal on the crimping face; and
inserting the anvil into the recess of the crimper, so that the terminal is crimped to an electric wire;
wherein a width of the receiving surface is not more than xc2xd of a thickness of the terminal.
Preferably, the width of the receiving surface may range from ⅕ to ⅖ of the thickness of the terminal.